The Galatasaray board took action after a disappointing 2021-22 season, in which the Istanbul giants finished 13th in the Turkish Süper Lig.
Galatasaray said in a statement: "We would like to thank Pasquale Sensibile for his services to our club and wish him success in his future career."
Ergün (pictured) was Director of Football at Galatasaray between 2015 and 2018, with that spell ending with a league title. He first joined the club in 2006 in an academy and player development role.
He told Galatasaray TV: "Our short-term goal is to create a team that is ready for the league this season. In the medium and long-term, it is primarily to create more opportunities for young people coming from the academy.
"It must be ensured that Galatasaray will aim for the top in every competition where it has a name. We can't promise the championship, but I can promise that we will go all the way."
One of Ergün's first tasks back at Galatasaray was to sign the club up to the TransferRoom platform in a bid to bring greater clarity and transparency to their transfer dealings.
Sensibile only joined Galatasaray in February 2022 on the recommendation of Luis Campos, the highly-renowned Portuguese Director of Football, who had been advising club President Burak Elmas.
Prior to that the experienced Italian executive had most recently been Chief Scout for AS Roma. He has also worked for Hellas Verona, Juventus, Palermo, Novara and Sampdoria in his home country.
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